Cervical remodeling is an essential part of normal pregnancy and is characterized by softening, shortening and dilation to allow for delivery at term. Errors in timing of these events may be associated with preterm birth. Currently, two of the main tools for assessment of the cervix include a cervical length measurement and digital palpation of `softness'. While the former is quantitative, the `softness' is subjectively determine by giving it a score of `soft', `medium', or `?rm'. The primary goal of this research is to develp a reliable, noninvasive method to quantitatively assess the structural integrity of the uterine cervi during pregnancy. Our preliminary studies show that Shear Wave Speed (SWS) estimation can objectively assess the softness of the cervix and that cystic structures perturb these estimates and should be avoided. However, other strong isolated scatterers such as blood vessels or dense collagen structures may also in?uence SWS estimates. We can use echo signal coherence to help guide location se- lection to avoid these structures for more robust SWS estimates. We have completed studies showing feasibility of SWS estimation in ex vivo hysterectomy specimens and in vivo third trimester pregnant subjects and demonstrated that the approach has merit. For the ?rst portion of this proposed investigation, ultrasound data has already been collected from a previous hysterectomy study and all samples have been ?xed in formalin. We plan to complete echo signal coherence analysis in order to identify collagen structures spatially that may in?uence SWS measurement and validate with microscopy of the ?xed samples. The second portion of this proposed investigation will test reproducibility and sensitivity of SWS estimation in vivo during the ?rst and second trimester of pregnancy. We will measure SWS in women undergoing cervical ripening procedures for early termination of pregnancy. Measurements will be made before and 4 hours after a cervical ripening agent is administered. Pre- and post-ripening SWS estimates will be compared within each woman and the 1st and 2nd trimester groups will be compared to the (nonpregnant) hysterectomy data and the 3rd trimester data already acquired. This proposal lays the foundation for understanding how cervical structural integrity changes throughout pregnancy which is essential for understanding normal and abnormal pregnancy. In addition, a full understanding of how structure in?uences quantitative ultrasound measure- ments will guide future in vivo study. The training plan includes ?eld work to be performed in Utah, in which the PI will be immersed in the clinical environment and have more involvement in management of 1st and 2nd trimester study.